Objective To investigate the correlation between serum calcium and glucose metabolism in patients with type 2 diabetes mellitus.Methods Three hundred and two cases of type 2 diabetics with normal renal function were divided into three groups according to their HbA1C levels:Better glycemic control group (HbA1C ≤7.0％),moderate glycemic control group (7.0％ ＜ HbA1C ≤ 9.0％),and poor glycemic control group (HbA1C ＞9.0％).Corrected serum calcium (CsCa) from the three groups were observed and compared and the correlation analysis and multiple stepwise regression were used to examine the correlations between CsCa and other indicators such as insulin resistance,pancreatic β cell function,HbA1C,and fasting plasma glucose.Results (1) Compared with better glycemic control group and moderate glycemic control group,the levels of CsCa [(2.26 ±0.12 vs 2.22 ±0.09,2.21 ± 0.11) mmol/L] and alkaline phosphatase in poor glycemic control group were higher while the levels of fasting insulin and homeostasis model assessment of β cell function (HOMA-β) were significantly lower (all P＜0.05).(2)In better glycemic control group,CsCa was negatively correlated with femur bone mineral density (P＜0.01) and positively correlated with insulin sensitivity index and total cholesterol (P ＜ 0.05) by multiple stepwise regression analysis.(3) In moderate glycemic control group,CsCa was negatively correlated with homeostasis model assessment of insulin resistance index (P＜0.01).(4) In poor glycemic control group,multiple stepwise analysis indicated that CsCa was negatively correlated with uric acid and HOMA-β (P＜0.01) and positively correlated with HbA1C (P＜0.01).Conclusions CsCa is closely correlated with the levels of glycemic control,insulin resistance,and pancreatic β cell function in patients with type 2 diabetes mellitus.